Daphne (plant)

Daphne /ˈdæfni/[3] (Greek: Δάφνη "laurel") is a genus of between 70 and 95 species of deciduous and evergreen shrubs in the family Thymelaeaceae, native to Asia, Europe and north Africa. They are noted for their scented flowers and often brightly coloured berries. Two species are used to make paper. Many species are grown in gardens as ornamental plants; the smaller species are often used in rock gardens. All parts of daphnes are poisonous, especially the berries.

Daphne
Daphne pontica in flower
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Malvales
Family: Thymelaeaceae
Subfamily: Thymelaeoideae
Genus: Daphne
L.[1]
Species

See text

Synonyms[2]
  • Daphmanthus F.K.Ward
  • Farreria Balf.f. & W.W.Sm. ex Farrer
  • Laureola Hill
  • Mezereum C.A.Mey.
  • Mistralia Fourr.
  • Nemoctis Raf.
  • Pentathymelaea Lecomte
  • Thymelaea All.
  • Tumelaia Raf.

Description

Daphne species are shrubs, with upright or prostrate stems. Upright species may grow to 1.5 m (5 ft). Their leaves are undivided, mostly arranged alternately (although opposite in D. genkwa), and have short petioles (stalks). The leaves tend to be clustered towards the end of the stems and are of different shapes, although always longer than wide. The leaf surface may be smooth (glabrous) or hairy.[4][5][6]

Many species flower in late winter or very early spring. The flowers are grouped into clusters (inflorescences), either in the leaf axils towards the end of the stems or forming terminal heads. The inflorescences lack bracts. Individual flowers completely lack petals and are formed by four (rarely five) petaloid sepals, tubular at the base with free lobes at the apex. They range in colour from white, greenish yellow or yellow to bright pink and purple. Most of the evergreen species have greenish flowers, while the deciduous species tend to have pink flowers. There are twice the number of stamens as sepals, usually eight, arranged in two series. Stamens either have short filaments or lack filaments altogether and are usually held inside the sepal tube. The style is short or absent, and the stigma is head-shaped (capitate).[4][5][6]

The ovary has a single chamber (locule). The fruits are one-seeded, and are either fleshy berries or dry and leathery (drupaceous[6]). When ripe the fruit is usually red or yellow, sometimes black.[4][5]

Taxonomy

The genus Daphne was first described by Carl Linnaeus in 1753 in Species Plantarum.[1] Linnaeus recognized 10 species, including Daphne mezereum, Daphne laureola and Daphne cneorum.[7] Some of his species are now placed in other related genera (e.g. Linnaeus's Daphne thymelaea is now Thymelaea sanamunda).[8] The number of species in the genus varies considerably between different authorities. The Flora of China states there are about 95 species, 41 of which are endemic to China. Some of these species were reduced to subspecies or varieties by Josef Halda in a series of papers from 1997 onwards,[9] culminating in a monograph on the genus.[10] Version 1.1 of The Plant List accepts 83 species.[11] The Flora of North America states there are 70 species.[6]

Phylogeny and generic limits

A 2002 study based on chloroplast DNA placed Daphne in a group of related genera; however there was only one species representing each genus.[12]

Edgeworthia

Wikstroemia

Stellera

Diarthron

Thymelaea

Daphne

A further study published in 2009 included an extra species of Wikstroemia and suggested that this genus was paraphyletic with respect to Stellera, but otherwise agreed with the cladogram above.[13] The distinction between Wikstroemia and Daphne is difficult to make; Halda included Wikstroemia within Daphne.[5] The cladogram shown above suggests that other genera would need to be included as well to make Daphne monophyletic.

Species

As of January 2023, Plants of the World Online accepts the following species:[14]

Hybrids

Hybrids accepted by Plants of the World Online are:[14]

  • Daphne × hauseri Halda
  • Daphne × hendersonii Hodgkin ex C.D.Brickell & B.Mathew – natural hybrid D. petraea × D. cneorum[4]
  • Daphne × houtteana Lindl. & Paxton
  • Daphne × juraseki Halda
  • Daphne × neapolitana (Lindl.) Loudon
  • Daphne × rossetii H.Correvon & Halda
  • Daphne × savensis Daksk., Seliškar & Vreš
  • Daphne × sillingeri Halda
  • Daphne × thauma Farrer – natural hybrid D. petraea × D. striata[4]

Numerous artificial hybrids are cultivated as ornamental plants. These include:

  • D. × burkwoodii[15] – D. cneorum × D. caucasica
  • D. × napolitana Lodd. has gained the Royal Horticultural Society's Award of Garden Merit[16] – origin not known[4]
  • D. × susannae C.D.Brickell – artificial hybrid D. arbuscula × D. sericea (syn. D. collina);[17] the correct name may be D. × medfordensis Halda[18]
  • D. × schlyteri – artificial hybrid D. cneorum × D. arbuscula[19]

Distribution

Daphne is a Eurasian genus, being native to central and southern Europe and Asia,[6] from Britain[20] to Japan.[21] Some species are also found in north Africa. Two species, D. mezereum and D. laureola, have been introduced into North America.[6]

Uses

Two species, Daphne bholua and Daphne papyracea, both called lokta, are sustainably harvested in Nepal and Bhutan for paper production.[22]

Many species are cultivated as ornamental shrubs in gardens.[23] The smaller species are used as rock garden plants or, in the case of those more difficult to grow, as plants for the alpine house. It is recommended that they are grown in well drained but moisture-retentive soil, avoiding strongly acid conditions. Most species prefer a sunny position, although some are woodland plants (e.g. D. mezereum and D. pontica). Propagation is by seed, cuttings or layering.[4]

Award of garden merit

The following species, hybrids and cultivars are recipients of the Royal Horticultural Society's Award of Garden Merit:

  • Daphne arbuscula[24]
  • Daphne bholua 'Jacqueline Postill' [25]
  • Daphne bholua var. glacialis 'Gurkha' [26]
  • Daphne × burkwoodii 'Somerset' [27]
  • Daphne cneorum 'Eximia' [28]
  • Daphne × rollsdorfii 'Wilhelm Schacht' [29]
  • Daphne tangutica Retusa Group [30]
  • Daphne × transatlantica Eternal Fragrance = 'Blafra' PBR[31]

Toxicity

All parts of daphnes are toxic, the berries being particularly so. One active compound is daphnin, a glycoside, combining glucose with daphnetin. Some species have been shown to contain a further toxin, mezerein. Symptoms of ingestion include burning sensations and lesions of the mouth and upper digestive tract, gastroenteritis and diarrhoea, and in severe cases, damage to the kidneys (nephritis), irregular heart rhythm, and coma.[32][33]

Allergenicity

Daphnes have an OPALS allergy scale rating of 5 out of 10, indicating moderate potential to cause allergic reactions, exacerbated by over-use of the same plant throughout a garden.[34] The sap and berry juice can cause dermatitis and the scent may affect the odor-sensitive.[34]

References
  1. "Plant Name Details for Daphne L.", The International Plant Names Index, retrieved 2017-11-23
  2. "Daphne Tourn. ex L." Plants of the World Online. Board of Trustees of the Royal Botanic Gardens, Kew. 2017. Retrieved 10 July 2020.
  3. Sunset Western Garden Book, 1995, pp. 606–607
  4. Beckett, K., ed. (1993), Encyclopaedia of Alpines : Volume 1 (A–K), Pershore, UK: AGS Publications, ISBN 978-0-900048-61-6, pp. 371–376
  5. Wang, Yinzheng; Gilbert, Michael G.; Mathew, Brian F. & Brickell, Christopher (1994), "Daphne", in Wu, Zhengyi; Raven, Peter H. & Hong, Deyuan (eds.), Flora of China, Beijing; St. Louis: Science Press; Missouri Botanical Garden, retrieved 2012-01-31
  6. Nevling Jr., Lorin I. & Barringer, Kerry, "Daphne", in Flora of North America Editorial Committee (ed.), Flora of North America (online), eFloras.org, retrieved 2017-11-22
  7. Linnæus, Carl (1753), "Daphne", Species Plantarum (in Latin), vol. 1, Stockholm, Sweden: Laurentius Salvius, p. 345, retrieved 2017-11-23
  8. "Thymelaea sanamunda", The Plant List, retrieved 2017-11-23
  9. Halda, Josef J. (1997), "Some nomenclatoric changes and new descriptions in the genus Daphne L." (PDF), Acta Musei Richnoviensis Sect. Nat., 4 (2): 67–70, archived from the original (PDF) on 2017-12-01, retrieved 2017-11-18
  10. Halda & Haldová (2001).
  11. "Search results for Daphne", The Plant List, retrieved 2017-11-19
  12. van der Bank, Michelle; Fay, Michael F. & Chase, Mark W. (2002), "Molecular Phylogenetics of Thymelaeaceae with particular reference to African and Australian genera", Taxon, 51 (2): 329–339, doi:10.2307/1554930, JSTOR 1554930
  13. Beaumont, Angela J.; Edwards, Trevor J.; Manning, John; Maurin, Olivier; Rautenbach, Marline; Motsi, Moleboheng C.; Fay, Michael F.; Chase, Mark W. & Van Der Bank, Michelle (2009), "Gnidia (Thymelaeaceae) is not monophyletic: taxonomic implications for Thymelaeoideae and a partial new generic taxonomy for Gnidia", Botanical Journal of the Linnean Society, 160 (4): 402–417, doi:10.1111/j.1095-8339.2009.00988.x icon of an open green padlock
  14. "Daphne Tourn. ex L.", Plants of the World Online, Royal Botanic Gardens, Kew, retrieved 2023-01-03
  15. RHS Plant Selector – Daphne × burkwoodii, retrieved 2013-06-14
  16. RHS Plant Selector - Daphne × napolitana, retrieved 2013-06-14
  17. "Daphne × susannae C.D.Brickell", International Plant Names Index (IPNI), Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens, retrieved 2019-05-09
  18. Jockel, Dirk M., "Daphne x medfordensis", Daphne – Seidelbast, archived from the original on 2020-07-06, retrieved 2020-07-06
  19. Mail Order Daphne from Junker's Nursery (38a), Junker's Nursery, archived from the original on 2009-10-04, retrieved 2012-01-29
  20. Stace, Clive (2010), "Daphne", New Flora of the British Isles (3rd ed.), Cambridge, UK: Cambridge University Press, pp. 381–382, ISBN 978-0-521-70772-5
  21. Ohwi, Jisaburo (1965), Meyer, Frederick G. & Walker, Egbert H. (eds.), Flora of Japan (in English), Washington, D.C.: Smithsonian Institution, p. 644, ISBN 978-0-87474-708-9, retrieved 2017-11-21
  22. Lokta Daphne sp. (PDF), Asia Network for Sustainable Agriculture and Bioresources (ANSAB), archived from the original (PDF) on 2007-02-25, retrieved 2014-03-01
  23. Phillips, Roger & Rix, Martyn (1989), Shrubs, London: Pan Books, ISBN 978-0-330-30258-6, pp. 36–39
  24. "Daphne arbuscula". RHS. Retrieved 5 May 2020.
  25. "Daphne bholua 'Jacqueline Postill'". RHS. Retrieved 5 May 2020.
  26. "Daphne bholua var. glacialis 'Gurkha'". RHS. Retrieved 5 May 2020.
  27. "Daphne × burkwoodii 'Somerset'". RHS. Retrieved 5 May 2020.
  28. "Daphne cneorum 'Eximia'". RHS. Retrieved 5 May 2020.
  29. "Daphne × rollsdorfii 'Wilhelm Schacht'". RHS. Retrieved 5 May 2020.
  30. "Daphne tangutica Retusa Group". RHS. Retrieved 5 May 2020.
  31. "Daphne × transatlantica Eternal Fragrance = 'Blafra' (PBR)". RHS. Retrieved 5 May 2020.
  32. Lewis, Robert A. (1998), "Daphne", Lewis' Dictionary of Toxicology, Boca Raton, etc.: Lewis Publishers, pp. 346–347, ISBN 978-1-56670-223-2, retrieved 2017-11-25
  33. Wink, M. (2009), "Mode of action and toxicology of plant toxins and poisonous plants", Mitteilungen aus dem Julius Kühn-Institut, 421: 93–112, retrieved 2017-11-25
  34. Ogren, Thomas Leo (2000). Allergy-Free Gardening. Berkeley, California: Ten Speed Press. ISBN 1580081665.

Bibliography
  • Brickell, C.D. & Mathew, B. (1976), Daphne: The Genus in the Wild and in Cultivation, Woking: The Alpine Garden Society, OCLC 832501497
  • Halda, Josef J. & Haldová, Jarmila (2001), The Genus Daphne, Dobré: SEN, ISBN 978-80-86483-00-9
  • White, Robin (2006), Daphnes: A Practical Guide for Gardeners, Portland, UK: Timber Press, ISBN 978-0-88192-752-8
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